Multi-layer anti-corrosive coating

ABSTRACT

Method of providing a multilayer coating. The method includes applying a first coating layer, which is substantially a metal, having a thickness of approximately 25 microns to approximately 200 microns directly on and in contact with a substrate; applying a second coating layer, which is a mixture of the metal and a polymeric material, having a thickness of approximately 5 microns to approximately 200 microns directly on and in contact with the first coating layer; applying a third coating layer, which is substantially the polymeric material, having a thickness of approximately 5 microns to approximately 200 microns directly on and in contact with the second coating layer; and at least one of: heating the substrate to approximately the fusing temperature of the metal when applying the first coating layer; and heating the substrate to approximately the fusing temperature of the polymeric material when applying the third coating layer.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of U.S. application Ser. No. 12/746,114, which is U.S. National Stage of International Application No. PCT/US08/85396 filed Dec. 3, 2008, which claims the benefit under 35 U.S.C. §119(e) of U.S. Provisional Application No. 60/992,143 filed Dec. 4, 2007, the disclosures of which are expressly incorporated by reference in their entireties.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

REFERENCE TO A COMPACT DISK APPENDIX

Not applicable.

DISCUSSION OF BACKGROUND INFORMATION

1. Field of the Invention

The invention relates generally to apparatus and methods relating to the application of coatings, and more particularly to a multilayer anti-corrosive coating for a metallic substrate such as an iron pipe.

2. Description of Related Art

Iron-based pipes have been used in transporting water from different sources for many years. Over time, these pipes exhibit corrosion and, depending on their use, may require frequent replacement. Replacing iron-based pipes is costly for the material, the labor, and the down-time to the consumer.

Cathodic protection is one technique used to control corrosion of a metal surface. This is done by making the surface to be protected the cathode of an electrochemical, or galvanic cell. This is most commonly done using alloys of zinc, magnesium and aluminum. These galvanic anodes are designed and selected to have a greater negative electrochemical potential than the metal they are protecting, which is typically steel. As the galvanic anode electrode corrodes, the anode material is consumed until it must be replaced.

Galvanizing, or more specifically hot-dip galvanizing is the process whereby steel is coated with a layer of metallic zinc. Galvanized coatings are extremely durable in most environments because of their barrier properties and cathodic protection. If, or when, the zinc coating is breached or scratched, exposing the steel surface, the zinc coating acts as an anode to form a galvanic cell, thereby protecting the steel from corrosion. This is also known as localized cathodic protection.

Coatings to iron-based pipes have also been developed utilizing epoxy compositions that result in good corrosion resistance. For example, thermoset polymers are widely used to protect steel pipes, concrete reinforcing bars (rebar), pipe connections, valves and the like from corrosion. The most commonly used thermoset polymer for this type of application is fusion bonded epoxy. Fusion bonded epoxy is typically applied to a steel pipe that is preheated to the application temperature where the fusion bonded epoxy transforms to a liquid. The liquid fusion bonded epoxy flows and solidifies on the pipe, pipe joint, and the like. Coating thickness of the fusion bonded epoxy is around 250 to 500 microns. However, the thickness of these coatings vary, are difficult to apply especially at the joints, and different coatings are required depending on the environmental exposure of the iron-based pipes.

With fusion bonded epoxy, any breach in the coating will result in corrosion of the coated material.

SUMMARY OF THE EMBODIMENTS

A multilayer coating that is corrosion resistant has a first coating layer on a substrate; a second coating layer deposited on the first coating layer; and a third coating layer deposited on the second coating layer; wherein the first coating layer is substantially a metal, the second coating layer is a mixture of the metal and a polymeric material, and the third coating layer is substantially the polymeric material.

Embodiments are directed to a method of providing a multilayer coating that includes applying a first coating layer, which is substantially a metal, having a thickness of approximately 25 microns to approximately 200 microns directly on and in contact with a substrate; applying a second coating layer, which is a mixture of the metal and a polymeric material, having a thickness of approximately 5 microns to approximately 200 microns directly on and in contact with the first coating layer; applying a third coating layer, which is substantially the polymeric material, having a thickness of approximately 5 microns to approximately 200 microns directly on and in contact with the second coating layer; and at least one of: heating the substrate to approximately the fusing temperature of the metal when applying the first coating layer; and heating the substrate to approximately the fusing temperature of the polymeric material when applying the third coating layer.

In embodiments, the substrate can include at least one of iron, iron alloy, steel, copper, alloys of copper, nickel, alloys of nickel, concrete, wood, wood products, fiberglass, ceramic and plastic.

In accordance with embodiments, the metal may include at least one of zinc, aluminum, alloy of zinc-aluminum, magnesium, alloy of zinc-magnesium, alloy of aluminum-magnesium, indium, alloy of zinc-indium, alloy of aluminum-indium, alloy of magnesium-indium, gallium, alloy of zinc-gallium, alloy of aluminum-gallium, alloy of magnesium-gallium, alloy of indium-gallium, tellurium, alloy of zinc-tellurian, alloy of aluminum-tellurium, alloy of magnesium-tellurium, alloy of indium-tellurium, and alloy of gallium-tellurium.

According to other embodiments, the polymeric material can include at least one of polyethylene, polypropylene, nylon, polytetrafluorethylene (PTFE), ethylene methacrylate acid copolymer (EMAA), a thermoplastic material and a thermoset material;

Embodiments are directed to a multilayer corrosion resistant coating that includes a first coating layer, which is substantially a metal, deposited directly on and in contact with a substrate; a second coating layer, which is a mixture of the metal and a polymeric material, deposited directly on and in contact with the first coating layer; and a third coating layer, which is substantially the polymeric material, deposited directly on and in contact with the second coating layer. The substrate includes at least one of steel, copper, alloys of copper, nickel, alloys of nickel, concrete, wood, wood products, fiberglass, ceramic and plastic; the metal includes at least one of zinc, aluminum, alloy of zinc-aluminum, magnesium, alloy of zinc-magnesium, alloy of aluminum-magnesium, indium, alloy of zinc-indium, alloy of aluminum-indium, alloy of magnesium-indium, gallium, alloy of zinc-gallium, alloy of aluminum-gallium, alloy of magnesium-gallium, alloy of indium-gallium, tellurium, alloy of zinc-tellurian, alloy of aluminum-tellurium, alloy of magnesium-tellurium, alloy of indium-tellurium, and alloy of gallium-tellurium; and the polymeric material includes comprises at least one of polyethylene, polypropylene, nylon, polytetrafluorethylene (PTFE), ethylene methacrylate acid copolymer (EMAA), a thermoplastic material and a thermoset material. A thickness of the first coating layer is approximately 25 microns to approximately 200 microns; a thickness of the second coating layer is approximately 5 microns to approximately 200 microns; and a thickness of the third coating layer is approximately 5 microns to approximately 200 microns.

According to embodiments, the metal can include at least 99% zinc.

In accordance with embodiments, the metal can include aluminum and zinc having an aluminum-zinc ratio of about 85% aluminum to about 15% zinc.

In other embodiments the substrate may be a metallic material, and the metal may be anodic to the substrate.

According to other embodiments, when the polymeric material includes thermoset material, the thermoset material can be a fusion bonded epoxy.

In accordance with still other embodiments, the first coating layer may be approximately 50-100 microns, the second coating layer may be approximately 5-100 microns, and the third coating layer may be approximately 50-150 microns.

In still other embodiments, the first coating layer can be approximately 70-80 microns, the second coating layer can be approximately 20-30 microns, and the third coating layer can be approximately 95-105 microns.

Embodiments are directed to a method of providing a multilayer coating that includes applying a first coating layer, which is substantially a metal, having a thickness of approximately 25 microns to approximately 200 microns directly on and in contact with a substrate, wherein the first coating layer is applied at a fusing temperature of the metal; applying a second coating layer, which is a mixture of the metal and a polymeric material, having a thickness of approximately 5 microns to approximately 200 microns directly on and in contact with the first coating layer, wherein the second coating layer is applied at a fusing temperature of the polymeric material; and applying a third coating layer, which is substantially the polymeric material, having a thickness of approximately 5 microns to approximately 200 microns directly on and in contact with the second coating layer, wherein the third coating layer is applied at the fusing temperature of the polymeric material.

According to embodiments, the first coating layer, the second coating layer and the third coating layer can be applied sequentially using at least one of cold spray, thermal spray and plasma spray.

In accordance with other embodiments, the method can also include at least one of: heating the substrate to approximately a fusing temperature of the metal when applying the first coating layer; and heating the substrate to approximately a fusing temperature of the polymeric material when applying the third coating layer.

In other embodiments, the applying of the second coating layer can include: applying the polymeric material onto an outer surface of the first coating layer; and embedding the metal into the polymeric material on the outer surface of the first coating layer.

According to still other embodiments, the applying of the second coating layer may include at least one of: mixing the polymeric material and the metal together prior to being applied as the second coating layer; and mixing the polymeric material and metal together upon impact at an outer surface on which the second coating layer is applied.

In accordance with still other embodiments, the substrate can include at least one of iron, iron alloy, steel, copper, alloys of copper, nickel, alloys of nickel, concrete, wood, wood products, fiberglass, ceramic and plastic.

In other embodiments, the metal can include at least one of zinc, aluminum, alloy of zinc-aluminum, magnesium, alloy of zinc-magnesium, alloy of aluminum-magnesium, indium, alloy of zinc-indium, alloy of aluminum-indium, alloy of magnesium-indium, gallium, alloy of zinc-gallium, alloy of aluminum-gallium, alloy of magnesium-gallium, alloy of indium-gallium, tellurium, alloy of zinc-tellurian, alloy of aluminum-tellurium, alloy of magnesium-tellurium, alloy of indium-tellurium, and alloy of gallium-tellurium.

In still other embodiments, the polymeric material may include at least one of polyethylene, polypropylene, nylon, polytetrafluorethylene (PTFE), ethylene methacrylate acid copolymer (EMAA), a thermoplastic material and a thermoset material.

In accordance with still yet other embodiments of the present invention, the multilayer coating can form a corrosion resistant coating for the substrate.

Other exemplary embodiments and advantages of the present invention may be ascertained by reviewing the present disclosure and the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is further described in the detailed description which follows, in reference to the noted drawing by way of a non-limiting example of an exemplary embodiment of the present invention, and wherein:

FIG. 1 is a cross section of a pipe with a multilayer coating.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The particulars shown herein are by way of example and for purposes of illustrative discussion of the embodiments of the present invention only and are presented in the cause of providing what is believed to be the most useful and readily understood description of the principles and conceptual aspects of the present invention. In this regard, no attempt is made to show structural details of the present invention in more detail than is necessary for the fundamental understanding of the present invention, the description taken with the drawings making apparent to those skilled in the art how the several forms of the present invention may be embodied in practice.

FIG. 1 shows a cross-sectional view of a substrate 10 having a multilayer corrosion resistant coating 12. The substrate 10 may be any of iron, iron pipe, steel, copper, nickel, concrete, wood, wood products, fiberglass, ceramic, plastic, and any other metal or non-metal material that can be used as a substrate. The corrosion resistant coating 12 is made up of three distinct coating layers 20, 30, 40.

The first coating layer 20 is substantially a metal layer that is applied using cold spray or thermal spray techniques. It is understood that thermal spray includes the use of various techniques, including, but not limited to, combustion flame, combustion wire, high velocity oxygen fuel (HVOF), high velocity liquid fuel (HVLF), high velocity air-fuel (HVAF), and plasma.

The metal 22 is typically at least one of zinc, aluminum, alloy of zinc-aluminum, magnesium, alloy of zinc-magnesium, alloy of aluminum-magnesium, indium, alloy of zinc-indium, alloy of aluminum-indium, alloy of magnesium-indium, gallium, alloy of zinc-gallium, alloy of aluminum-gallium, alloy of magnesium-gallium, alloy if indium-gallium, tellurium, alloy of zinc-tellurian, alloy of aluminum-tellurium, alloy of magnesium-tellurium, alloy of indium-tellurium, and alloy of gallium-tellurium. Other metals may also be considered. In one embodiment, the substrate 10 is iron pipe and the first coating layer 20 is a metal 22 that is anodic to the substrate 10. When this is the configuration, the metal 22 is preferably one of 99% zinc and aluminum-zinc having a ratio of about 85% aluminum to about 15% zinc, and the thickness 24 of the first coating layer is approximately 25 microns to approximately 200 microns. In another embodiment the thickness 24 of the first coating layer is approximately 70-80 microns.

In one embodiment the first coating layer 20 is applied utilizing thermal spray techniques, where the metal 22 is fed as a powder or a wire. The metal 22 is preferably applied at the fusing temperature of the anode, that is, for example, if the substrate 10 is an iron pipe and the metal 22 is zinc, the fusing temperature is approximately 850° F.

The second coating layer 30 is a mixture of the metal 22 and a polymeric material 32. The polymeric material 32 may be applied using thermal spray or cold spray techniques. The polymeric material 32 is at least one of polyethylene, polypropylene, polyester, nylon, polytetrafluorethylene (PTFE), ethylene methacrylate acid copolymer (EMAA), a thermoplastic material and a thermoset material. In one embodiment the polymeric material 32 is at least one of polyethylene and polypropylene. The thickness 34 of the second coating layer 30 is approximately 5 microns to approximately 200 microns. In another embodiment, the thickness 34 of the second coating layer 30 is approximately 20-30 microns.

The second coating layer 30 is preferably applied utilizing thermal spray techniques, where the polymeric material 32 is powder fed through a hopper. The polymeric material 32 is preferably applied at the fusing temperature of the polymeric material 32, that is, for example, at a temperature of approximately 450° F.

In one embodiment, the metal 22 and the polymeric material 32 are applied substantially simultaneously from two or more applicator guns, the mixing occurring at the deposition site.

The third coating layer 40 is made up essentially of the polymeric material 32. The polymeric material 32 may be applied using thermal spray or cold spray techniques. The polymeric material 32 is at least one of polyethylene, polypropylene, polyester, nylon, polytetrafluorethylene (PTFE), ethylene methacrylate acid copolymer (EMAA), a thermoplastic material and a thermoset material. In the preferred embodiment the polymeric material 32 is at least one of polyethylene and polypropylene. The thickness 44 of the third coating layer 40 is approximately 5 microns to approximately 200 microns. In the preferred embodiment, the third thickness 44 of the third coating layer is approximately 95-105 microns.

The third coating layer 40 is preferably applied utilizing thermal spray techniques, where the polymeric material 32 is powder fed through a hopper. The polymeric material 32 is preferably applied at the fusing temperature of the polymeric material 32, that is, for example, at a temperature of approximately 450° F. This is similar to the application of the polymeric material as part of the second layer.

The multi-layer coating 12 is applied to the substrate 10 by first applying the first coating layer 20 onto the substrate 10. This is followed by applying the second coating layer 30 onto the first coating layer. The second coating layer 30 is applied by spraying a mixture of the metal 22 used in the first layer 20 with a polymeric material 32.

It should be noted that the second coating layer 30 can be applied to the first coating layer 20 utilizing a single spray gun or a multiple spray gun method. When a two spray gun method is used, the metal 22 is sprayed from a first spray gun towards the outer surface of the first coating layer 20 while the polymeric material 32 is sprayed from a second spray gun towards the outer surface of the first coating layer 20. Mixing of the coating materials 22, 32 takes place, for example, prior to the coating material reaching the outer surface of the first coating layer 20 by firing the spray guns substantially simultaneously, or upon impact at the outer surface of the first coating layer 20.

In one embodiment, the polymeric coating material 32 is applied first to the outer layer of the first coating layer 20, and the metal coating material 22 embeds into the polymeric material 32 forming the second coating layer 30.

In another embodiment, the multiple spray guns release the coating materials 22, 32 substantially simultaneously to form the second coating layer 30.

It is noted that the foregoing examples have been provided merely for the purpose of explanation and are in no way to be construed as limiting of the present invention. While the present invention has been described with reference to an exemplary embodiment, it is understood that the words which have been used herein are words of description and illustration, rather than words of limitation. Changes may be made, within the purview of the appended claims, as presently stated and as amended, without departing from the scope and spirit of the present invention in its aspects. Although the present invention has been described herein with reference to particular means, materials and embodiments, the present invention is not intended to be limited to the particulars disclosed herein; rather, the present invention extends to all functionally equivalent structures, methods and uses, such as are within the scope of the appended claims. 

What is claimed as new and desired to be protected by Letters Patent of the United States is:
 1. A method of providing a multilayer coating comprising: applying a first coating layer, which is substantially a metal, having a thickness of approximately 25 microns to approximately 200 microns directly on and in contact with a substrate; applying a second coating layer, which is a mixture of the metal and a polymeric material, having a thickness of approximately 5 microns to approximately 200 microns directly on and in contact with the first coating layer; applying a third coating layer, which is substantially the polymeric material, having a thickness of approximately 5 microns to approximately 200 microns directly on and in contact with the second coating layer; and at least one of: heating the substrate to approximately the fusing temperature of the metal when applying the first coating layer; and heating the substrate to approximately the fusing temperature of the polymeric material when applying the third coating layer.
 2. A method of providing a multilayer coating according to claim 1, wherein the substrate comprises at least one of iron, iron alloy, steel, copper, alloys of copper, nickel, alloys of nickel, concrete, wood, wood products, fiberglass, ceramic and plastic.
 3. A method of providing a multilayer coating according to claim 1, wherein the metal comprises at least one of zinc, aluminum, alloy of zinc-aluminum, magnesium, alloy of zinc-magnesium, alloy of aluminum-magnesium, indium, alloy of zinc-indium, alloy of aluminum-indium, alloy of magnesium-indium, gallium, alloy of zinc-gallium, alloy of aluminum-gallium, alloy of magnesium-gallium, alloy of indium-gallium, tellurium, alloy of zinc-tellurian, alloy of aluminum-tellurium, alloy of magnesium-tellurium, alloy of indium-tellurium, and alloy of gallium-tellurium.
 4. A method of providing a multilayer coating according to claim 1, wherein the polymeric material comprises at least one of polyethylene, polypropylene, nylon, polytetrafluorethylene (PTFE), ethylene methacrylate acid copolymer (EMAA), a thermoplastic material and a thermoset material;
 5. A multilayer corrosion resistant coating comprising: a first coating layer, which is substantially a metal, deposited directly on and in contact with a substrate; a second coating layer, which is a mixture of the metal and a polymeric material, deposited directly on and in contact with the first coating layer; and a third coating layer, which is substantially the polymeric material, deposited directly on and in contact with the second coating layer; wherein the substrate comprises at least one of steel, copper, alloys of copper, nickel, alloys of nickel, concrete, wood, wood products, fiberglass, ceramic and plastic; wherein the metal comprises at least one of zinc, aluminum, alloy of zinc-aluminum, magnesium, alloy of zinc-magnesium, alloy of aluminum-magnesium, indium, alloy of zinc-indium, alloy of aluminum-indium, alloy of magnesium-indium, gallium, alloy of zinc-gallium, alloy of aluminum-gallium, alloy of magnesium-gallium, alloy of indium-gallium, tellurium, alloy of zinc-tellurian, alloy of aluminum-tellurium, alloy of magnesium-tellurium, alloy of indium-tellurium, and alloy of gallium-tellurium; wherein the polymeric material comprises at least one of polyethylene, polypropylene, nylon, polytetrafluorethylene (PTFE), ethylene methacrylate acid copolymer (EMAA), a thermoplastic material and a thermoset material; wherein a thickness of the first coating layer is approximately 25 microns to approximately 200 microns; wherein a thickness of the second coating layer is approximately 5 microns to approximately 200 microns; and wherein a thickness of the third coating layer is approximately 5 microns to approximately 200 microns.
 6. The multilayer corrosion resistant coating of claim 5, wherein the metal comprises at least 99% zinc.
 7. The multilayer corrosion resistant coating of claim 5, wherein the metal comprises aluminum and zinc having an aluminum-zinc ratio of about 85% aluminum to about 15% zinc.
 8. The multilayer corrosion resistant coating of claim 5, wherein the substrate is a metallic material, and wherein the metal is anodic to the substrate.
 9. The multilayer corrosion resistant coating of claim 5, wherein, when the polymeric material comprises thermoset material, the thermoset material is a fusion bonded epoxy.
 10. The multilayer corrosion resistant coating of claim 5, wherein the first coating layer is approximately 50-100 microns, the second coating layer is approximately 5-100 microns, and the third coating layer is approximately 50-150 microns.
 11. The multilayer corrosion resistant coating of claim 5, wherein the first coating layer is approximately 70-80 microns, the second coating layer is approximately 20-30 microns, and the third coating layer is approximately 95-105 microns.
 12. A method of providing a multilayer coating comprising: applying a first coating layer, which is substantially a metal, having a thickness of approximately 25 microns to approximately 200 microns directly on and in contact with a substrate, wherein the first coating layer is applied at a fusing temperature of the metal; applying a second coating layer, which is a mixture of the metal and a polymeric material, having a thickness of approximately 5 microns to approximately 200 microns directly on and in contact with the first coating layer, wherein the second coating layer is applied at a fusing temperature of the polymeric material; and applying a third coating layer, which is substantially the polymeric material, having a thickness of approximately 5 microns to approximately 200 microns directly on and in contact with the second coating layer, wherein the third coating layer is applied at the fusing temperature of the polymeric material.
 13. The method of providing the multilayer coating of claim 12, wherein the first coating layer, the second coating layer and the third coating layer are applied sequentially using at least one of cold spray, thermal spray and plasma spray.
 14. The method of providing the multilayer coating of claim 12, further comprising at least one of: heating the substrate to approximately a fusing temperature of the metal when applying the first coating layer; and heating the substrate to approximately a fusing temperature of the polymeric material when applying the third coating layer.
 15. The method of providing the multilayer coating of claim 12, wherein the applying of the second coating layer comprises: applying the polymeric material onto an outer surface of the first coating layer; and embedding the metal into the polymeric material on the outer surface of the first coating layer.
 16. The method of providing the multilayer coating of claim 12, wherein the applying of the second coating layer comprises at least one of: mixing the polymeric material and the metal together prior to being applied as the second coating layer; and mixing the polymeric material and metal together upon impact at an outer surface on which the second coating layer is applied.
 17. The method of providing a multilayer coating according to claim 12, wherein the substrate comprises at least one of iron, iron alloy, steel, copper, alloys of copper, nickel, alloys of nickel, concrete, wood, wood products, fiberglass, ceramic and plastic.
 18. The method of providing a multilayer coating according to claim 12, wherein the metal comprises at least one of zinc, aluminum, alloy of zinc-aluminum, magnesium, alloy of zinc-magnesium, alloy of aluminum-magnesium, indium, alloy of zinc-indium, alloy of aluminum-indium, alloy of magnesium-indium, gallium, alloy of zinc-gallium, alloy of aluminum-gallium, alloy of magnesium-gallium, alloy of indium-gallium, tellurium, alloy of zinc-tellurian, alloy of aluminum-tellurium, alloy of magnesium-tellurium, alloy of indium-tellurium, and alloy of gallium-tellurium.
 19. The method of providing a multilayer coating according to claim 12, wherein the polymeric material comprises at least one of polyethylene, polypropylene, nylon, polytetrafluorethylene (PTFE), ethylene methacrylate acid copolymer (EMAA), a thermoplastic material and a thermoset material.
 20. The method of providing a multilayer coating according to claim 12, wherein the multilayer coating forms a corrosion resistant coating for the substrate. 